The present invention relates to a cleaning device for a transferring system in a wet-type copying machine.
Previously known cleaning devices used with such a copying machine included a cleaning roller which is turned in the same direction as the direction of rotation of the photosensitive drum of the copying machine by contact with the generating line of the photosensitive drum and a cleaning blade in contact with the outer wall of the photosensitive drum to scrape off toner remaining on the drum. Such devices suffer from a difficulty in that, if the copying machine is not used for a long period of time, the solvent in the developing solution evaporates as a result of which the toner accumulated between the cleaning roller and the cleaning blade is solidified making it difficult to turn the photosensitive drum. At worst, it is completely impossible to start the operation of the copying machine. In addition, the repetitive use of the cleaning roller causes the toner to enter the cleaning roller and to accumulate therein as a result of which the volume and elasticity of the cleaning roller are reduced. Accordingly, the cleaning performance of the cleaning device is lowered and reproduced images become smudged making the quality of the reproduced images unacceptably low.
In order to overcome these difficulties, a method has been proposed in the art in which a developing solution or a solvent is dropped onto the cleaning roller and the cleaning blade to prevent the solidification of the toner. However, that method is disadvantageous in that the evaporation rate of the solvent is considerably increased. In order to eliminate the above-described difficulties, the copying machines must be inspected at shorter maintenance intervals which is bothersome and costly.
In some copying machines, a step is formed at the end of the photosensitive drum to separate a transferring sheet from the drum with a separating guide. More specifically, the transferring sheet is laid on the photosensitive drum in such a manner that it extends slightly beyond the drum in the axial direction thereof so that the transferring sheet is engaged with the separating guide. In such copying machines, the transferring sheet is pulled up by the separating guide and is then forwarded to the following stage. If in this operation the end face of the photosensitive is dirty or stained, a black line is formed on the transferring sheet.
In general, the cleaning roller is made longer than the photosensitive drum of the copying machine. This causes the developing solution to ooze out on both end faces of the drum. However, the end faces of the drum cannot be cleaned with the cleaning roller and are cleaned with the cleaning blade only. Accordingly, a black line may be formed on parts of the transferring sheet which extend beyond the drum along the edge of the end face of the drum.
Furthermore, the toner has a tendency to remain on the blade plate of the cleaning blade. After a copying machine has been operated for a long period of time, the toner will accumulate considerably which lowers the cleaning performance of the cleaning device.